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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright (c) 2008-2009, The KiWi Project (http://www.kiwi-project.eu)
 * All rights reserved.
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 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice, 
 *   this list of conditions and the following disclaimer.
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
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 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
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 * 
 * Contributor(s):
 * sschaffe
 * 
 */
package kiwi.core.api.rdfa;

import java.util.List;

import kiwi.core.service.rdfa.JSFRDFaNode;
import kiwi.core.service.rdfa.JSFRDFaProperty;

/**
 * The JSFRDFaService provides access to the RDF context from JSF templates. The RDF context offers the following 
 * EL expressions:
 * <ul>
 *   <li>rdf.getResource(URI) returns a suitable representation of the resource identified by the given URI</li>
 * </ul>
 *
 * @author Sebastian Schaffert
 *
 */
public interface JSFRDFaService {

	/**
	 * Return a JSF+RDFa wrapper around the resource identified by the given URI.
	 * 
	 * @param uri
	 * @return
	 */
	public JSFRDFaNode getResource(String uri);
	
	/**
	 * Return a JSF+RDFa wrapper around the resource of the currently active content item (currentContentItem).
	 * 
	 * @return
	 */
	public JSFRDFaNode getCurrentResource();
	
	/**
	 * Remove the relation (triple) wrapped by the property passed as argument. Needed in action items.
	 * 
	 * @param prop
	 */
	public void removeRelation(JSFRDFaProperty prop);
	

	/**
	 * Flushes the relation currently held in the page-scoped variable "newProperty" and commits the transaction, 
	 * saving all updated properties and nodes.
	 */
	public void addRelation();
	
	/**
	 * Return a list of wrappers around RDF resources and literals determined by a query in one of the languages 
	 * supported by KiWi (e.g. SPARQL, KWQL, KIWI). The items in the list themselves are read only.
	 * 
	 * @param query
	 * @param language
	 * @return
	 */
	public List<JSFRDFaNode> query(String query, String language) throws JSFRDFaException;
}
